Along with the booming development of the flat panel display technique, OLED (organic light-emitting diode) displays, in comparison with conventional liquid crystal displays (LCDs), not only are thinner and lighter, but also have many excellent properties, such as self-illumination, low power consumption, no back light requirement, no viewing angle restriction, high response speed, and etc., thus OLED displays have become the main trend of next generation of flat panel display technique and are used more and more widely.
The unique advantages of OLED devices have close relationships with the current carrier transfer materials, luminescent materials and electrode materials used in the devices, and the structures of the devices, wherein, luminescent material is a key part of the OLED device and can be divided into two types: fluorescent materials and phosphorescent materials. Fluorescent light is generated by electron transition between homogenous multiplets, and the maximum efficiency is only 25%. The low luminescence efficiency of fluorescent materials is caused by the limitation of the luminescence mechanism thereof.